...and they vary in cup height as well. Nominal diameter is pretty constant across brands in intended use but height varies a bit. Good rule of thumb is use the recommended (in this case by Sierra) for their projectiles. They have well paid ballisticians on staff that do nothing but build and analyize different loads.

I really didn't realize the difference in cup height until I started modifying black powder rifles. Especially 209 primers are all over the place cup height wise between manufacturers and even between lots.

I stay away from the off brands of primers (I realize that primers are hard to come by right) now so you need to use some preplanning and order what you require and wait patiently.